Electrical conductivity is an important parameter for the operation of many devices. As devices become smaller, there has been a need at improving electrical conductivity without increasing the size of the conductive entity or even a need for a reduction in size. The size of conducting members can play a role in the development and improvement of transparent electrodes, electromagnetic wave shielding films, antistatic agents, solar cells and the like.
Currently, electrical conductivity is achieved in transparent films by application of a thin metallic coating such as gold, silver or copper, or a metal oxide coating such as Indium Tin Oxide (ITO). Transparent conductive oxide films such as ITO are used in a wide variety of applications such as for window de-icers, heat reflectors, LCDs, organic light emitting diodes (OLEDs), solar cells, and architectural coatings. However, ITO coatings have many limitations such as weak mechanical strength and low flexibility, which can result in being fragile and readily damaged during bending. Also, the ITO coatings are generally applied using vacuum deposition, and are not able to form patterns or circuits. Also, the high raw material cost of indium and the chemical stability in some device structures limit potential applications. For better conductivity control and mechanical property demands (i.e., flexibility, expansion coefficient, etc), alternative highly conductive materials with more favorable mechanical properties are needed. Moreover, in consideration of the display industry pursuing light weight-, low cost- and large size-products, there is a need to develop conductive materials to improve upon and advance past ITO.
Some conductive materials that may replace ITO can include carbon nanotubes, conductive polymers, or their composite materials. Single wall carbon nanotubes (SWCNTs) are candidates for a transparent conductive film, since they are robust, giving them the potential to be deposited on plastic and flexed with no degradation in electrical conductivity. Carbon nanotube coatings may require less loading (per weight percent) than other conductive particles.